Baseband controller in a wireless local area network

ABSTRACT

A baseband controller includes a microsequencer with special hardware resources circuitry and a configuration that supports real-time Bluetooth functionality for an upper limit of Bluetooth slave devices. The microsequencer includes a 72-bit correlator that may also be used as an accumulator, wherein the topology provides that the correlator can communicate with a 72-bit arithmetic logic unit that correspondingly enables the correlator to act as an accumulator. The microsequencer also includes a plurality of clocks and timers for facilitating Bluetooth timing functionality, and at least four registers for temporarily storing computational data, where each of the storage registers have different sizes for accommodating different-sized packets of computational data.

The present application is a continuation of U.S. patent applicationSer. No. 10/007,435, entitled “BASEBAND CONTROLLER IN A WIRELESS LOCALAREA NETWORK,” filed Nov. 8, 2001, which is hereby incorporated hereinby reference in its entirety and are made part of the present U.S.patent application for all purposes.

BACKGROUND

1. Technical Field

The present invention relates to wireless communication systems and,more specifically, micro-controllers used in wireless communicationsystems.

2. Related Art

The Bluetooth wireless technology allows users to make effortless,wireless and instant connections between various communication devicessuch as notebook computers, desktop computers and mobile phones. BecauseBluetooth systems use radio frequency transmissions to transfer bothvoice and data, the transmissions occur in real-time. The Bluetoothspecification provides for a sophisticated transmission mode thatensures protection from interference and provides security of thecommunication signals.

According to most designs that implement the Bluetooth specifications,the Bluetooth radio is being built into a small microchip and isdesigned to operate in frequency bands that are globally available. Thisensures communication compatibility on a worldwide basis. Additionally,the Bluetooth specification defines two power levels. A first powerlevel covers the shorter, personal area within a room and a second powerlevel is designed for covering a medium range. For example, the secondpower level might be used to cover communications from one end of abuilding, such as a house, to the other. Software controls and identitycoding are built into each microchip to ensure that only those unitspreset by the owners can communicate with each other.

More specifically, the Bluetooth wireless technology supportspoint-to-point and point-to-multipoint connections. Under the Bluetoothspecifications, one master can communicate with up to seven slavedevices. At any one instant, a Bluetooth master can communicate ortransmit over three channels to the slaves under current specificationsand designs. Additionally, one group of Bluetooth devices, namely amaster and a plurality of slaves, may also communicate with anothergroup to create communication networks of continually configurable andflexible configurations. The topology is best described as a flexibleand extendible micronetwork.

The Bluetooth specification is made to facilitate compatibility amongsystems made by different vendors and sold and utilized throughout theworld. At the same time, the Bluetooth protocols and specifications areopen to enable the use of proprietary processes underneath the definedcommunication protocols. The Bluetooth protocol stack can be dividedinto four layers, notwithstanding that it allows for proprietaryimplementation, according to the purposes and aspects of the protocol.For example, the core Bluetooth protocol defines the protocols forbaseband operation, as well as the link manager protocol (LMP), logicallink and control adaptation protocol (L2CAP), and service discoveryprotocol (SDP).

The second protocol layer is the cable replacement protocol thatincludes the serial cable emulation protocol (RSCOMM). The thirdprotocol layer is the telephony control protocols which includes thetelephony control specification (TCS binary) and the AT commands.Finally, the fourth protocol layer includes the adopted protocols, suchas point-to-point protocol (PPP), transport control protocol/userdatagram protocol (TCP/UDP), object exchange protocol (OEP), wirelessapplication protocol (WAP), WAP application environment (WAE) andothers. In addition to the above mentioned protocol layers, theBluetooth specification also defines a host controller interface (HCI).HCI provides a command interface to the baseband controller, linkmanager, as well as access to hardware status and control registers.

The Bluetooth core protocols include Bluetooth-specific protocols thathave been developed for Bluetooth systems. For example, the RFCOMM andTCS binary protocol have also been developed for Bluetooth but they arebased on the ETSI TS 07.10 and the ITU-T recommendations Q.931standards, respectively. Most Bluetooth devices require the Bluetoothcore protocols, in addition to the Bluetooth radio, while the remainingprotocols are only implemented when necessary.

The cable replacement layer, the telephone control layer and the adoptedprotocol layer form application-oriented protocols that enableapplications to run on top of or over the Bluetooth core protocols.Because the Bluetooth specification is open, these additional protocolsmay be accommodated in an inoperable fashion that is not necessarilyrequired.

The baseband and link control layers facilitate the physical operationof the Bluetooth transceiver and, more specifically, the physical RFlink between Bluetooth units forming a network. As the Bluetoothstandards provide for frequency-hopping in a spread spectrum environmentin which packets are transmitted in continuously changing defined timeslots on defined frequencies, the baseband and link control layerutilizes inquiry and paging procedures to synchronize the transmissionof communication signals at the specified frequency and clock cyclesbetween the various Bluetooth devices.

The Bluetooth core protocols further provide two different types ofphysical links with corresponding baseband packets. A synchronousconnection-oriented (SCO) and an asynchronous connectionless (ACL)physical link may be implemented in a multiplexed manner on the same RFlink. ACL packets are used for data only while the SCO packets maycontain audio, as well as a combination of audio and data. All audio anddata packets can be provided with different levels of error correctionand may also be encrypted if required. Special data types, includingthose for link management and control messages, are transmitted on aspecial specified channel.

The Bluetooth protocols are intended for rapidly developing applicationsusing Bluetooth technology. These applications include an ultimateheadset, three-in-one phone, local network access, file transfer andInternet bridge. Because of the different types of applications that areenvisioned for Bluetooth systems, several aspects of the communicationprotocols are very important. One requirement for a Bluetooth device isto be able to communicate and transfer its signals in a real-time basis.Another requirement that is extremely important for a Bluetooth systemis that it be able to transmit and receive and interpret transmissionsat exact moments in time. In the context of a Bluetooth network thatincludes one master and seven slaves, the synchronization and timingrequirements for the communications can be significant for any onedevice. Current microsequencers and controllers, for example, do nothave the capability to communicate with up to seven slaves on areal-time basis because it is impossible for any one micro-controller tosatisfy the real-time Bluetooth requirements. For example, the internaldata pipelines and supporting hardware to facilitate such communicationsdo not readily support this requirement that is found in the Bluetoothspecification. Stated differently, the data pipeline designs of mastersand micro-controllers cannot readily process all of the data for sevenslaves on a real-time basis. Accordingly, what is needed is a devicethat provides the ability for a master to communicate with up to sevenother devices concurrently and on a real-time basis while satisfyingBluetooth timing requirements.

SUMMARY

The present invention is directed to apparatus and methods of operationthat are further described in the following Brief Description of theDrawings, the Detailed Description of the Drawings, and the Claims.Other features and advantages of the present invention will becomeapparent from the following detailed description of the invention madewith reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention can be obtained when thefollowing detailed description of the preferred embodiment is consideredwith the following drawings, in which:

FIG. 1 is a functional block diagram of a Bluetooth micro network formedaccording to one embodiment of the present invention;

FIG. 2 illustrates a “transmit and receive” cycle for a Bluetoothtransmission;

FIG. 3 is a functional block diagram of a microsequencer formedaccording to one embodiment of the present invention;

FIG. 4 is a functional block diagram of one embodiment of specialhardware resources circuitry; and

FIG. 5 is a functional schematic block diagram of a microsequencerconfigured as a real-time Bluetooth baseband controller.

DETAILED DESCRIPTION OF THE DRAWINGS

Because a master in a Bluetooth network may communicate with up to sevenslaves, and because the Bluetooth requirements are timing-oriented, theability of a system to satisfy the Bluetooth requirements for each ofthe seven slaves can be difficult. A microsequencer is formed to includespecial hardware resources and a configuration that facilitates usingthe microsequencer as a real-time Bluetooth baseband controller toservice such a plurality of slave devices.

FIG. 1 is a functional block diagram of a Bluetooth micro network formedaccording to one embodiment of the present invention. As may be seen, aBluetooth master 104 communicates with a plurality of slaves 108 and110. More specifically, master 104 communicates with slave 108 overcommunication link 112. Each of the previously mentioned communicationlayer exchanges may occur between master 104 and the slaves 108 and 110at any time. Additionally, any one of the slave devices, such as slave108, may execute each of the aforementioned applications. For example,one slave might be an interface to a wireless modem, while another mightbe an interface to a broadband modem to wirelessly link a user device byway of the Bluetooth master 104 and slaves 108 and 110, thereto.

Others of the slave devices 110 shown here in FIG. 1 might comprisecommunication devices that operate with user devices of a completelydifferent type. For example, at least some of the slaves shown in FIG. 1might be high performance speakers. In this example, the Bluetoothsystem would be used to deliver audio for playback by the speakers.Thus, as may be seen, one Bluetooth network is able to not only transmitaudio signals for speakers to play for entertainment purposes, but alsoto transmit data signals to a specified communication device to enablethe user to “surf” the web while listening to his/her favorite music.

FIG. 2 illustrates a “transmit and receive” cycle for a Bluetoothtransmission. Referring now to FIG. 2, signal 200 illustrates a typicalBluetooth signal layout. This signal layout applies to transmittedsignals as well as received signals. Signal 200 includes an ID portion204, a packet header portion 208, a payload portion 212, a reservedbuffer portion 216 and an processing time portion 220. As may be seen,two Bluetooth clock cycles totaling 625 microseconds are shown.Initially, the first 72 microseconds are allocated for transmitting IDportion 204. The subsequent 54 microseconds are then allocated fortransmitting packet header information Thereafter, the remaining timefor the first Bluetooth clock cycle is for transmitting data, controlcommands, status commands, etc., in payload portion 212.

The second Bluetooth clock cycle includes reserved portion 216. Reservedportion 216 is, effectively, a buffer portion to allow for task orcommunication completion. For example, it is for received skewed signalsthat are being received late. Thus, a Bluetooth system may receive datain this portion but only because of operational variations that resultfrom unplanned delays or skewing. In the described embodiment, thereserved portion 216 is approximately 27.5 microseconds long. Once thereserved portion 216 is expired, processing portion 220 allows theBluetooth device time to process data or prepare for a subsequenttransmission/reception. Thereafter, the Bluetooth device is in alistening mode to receive transmissions from another Bluetooth device.

FIG. 3 is a functional block diagram of a microsequencer formedaccording to one embodiment of the present invention. A microsequencer300 includes a 32-bit microcode read-only memory 304 that is for storingmicrocode (computer instructions that define the operational logic ofthe microsequencer of FIG. 3. Microcode read-only memory 304 further iscoupled to receive control signals from a program counter (PC) 308 thatfurther communicates with a stack 312. The control commands from PC 308select what instruction(s) is(are) sent to a control decode module 316.Control decode module 316 is coupled to receive computer instructionsproduced by microcode read-only memory 304 and to execute the receivedinstructions in accordance with the logic defined within microcodememory 304. Control decode module 316 further generates control commandsto PC 308 to prompt it to change its program counter value (andtherefore what instructions are sent from microcode ROM 304 to controldecode module 316.

A random access memory and core registers module 320 is coupled tocommunicate with a 72-bit correlator 324. 72-bit correlator 324 furtheris coupled to receive input data from an external source and to produceoutput data to an external source. The 72-bit correlator 324 further iscoupled to communicate over line 326 with multiplexers 332 and 336. Themultiplexers 332 and 336 further communicate with a 72-bit arithmeticlogic unit 340. In addition to the above circuitry, microsequencer 300includes hardware modules to provide Bluetooth specific resources tofacilitate real-time communications with up to seven slaves as isrequired by the Bluetooth specification. The special hardware resourcesare collectively shown as special hardware resources 328 in FIG. 3. Asmay also be seen, 72-bit correlator 324, as well as 72-bit arithmeticlogic unit 340 and special hardware resources 328, each transmitcondition signals 344, 352 and 348, respectively, to control decodemodule 316 that reflect status and operational conditions.

One aspect of the microsequencer 300 is that it includes a 72-bitcorrelator 324 that may be used as an accumulator. Moreover, the datawithin 72-bit correlator 324 may also be transmitted to 72-bitarithmetic logic unit 340 by way of multiplexers 332 and 336.Accordingly, a value received within the 72-bit correlator 324 may betransmitted to 72-bit arithmetic logic unit 340 for processing in agiven computation. The coupling of 72-bit correlator 324 to 72-bitarithmetic logic unit 340 is new. Moreover, such coupling by way ofdemultiplexers 332 and 336 also is new. Finally, as may be seen, 72-bitcorrelator 324 and special hardware resources circuitry 328 are coupledto produce condition signals, namely, status signals, flags andinterrupts to control decode module 316 by way of condition signals 344and 348, respectively.

FIG. 4 is a functional block diagram of one embodiment of specialhardware resources circuitry 328, as shown in FIG. 3. Referring now toFIG. 4, three areas are shown generally at 404, 408 and 412 thatillustrate some of the circuitry that has been included into amicrosequencer that operates as a Bluetooth baseband controller. Thecircuitry portion shown generally at 404 includes a plurality of timersand their corresponding timer control logic 402. The special hardwareresources circuitry 400, which represents one embodiment of the specialhardware resources circuitry 328 of FIG. 3, includes eight timers andtheir corresponding timer control logic 402 in circuitry portion 404. Aswill be explained in greater detail below, the special hardwareresources circuitry 400 comprises four clocks in the describedembodiment. The timers of circuitry portion 404 operate to count anelapsed amount of time and are driven by one of the four clocks foundwithin special hardware resources circuitry 400. In general, the timercontrol logic 402 operates to receive a requested timer counting valuefrom a device needing to know when a specified amount of time haselapsed and to assign that requested count value to one of the eighttimers. Thereafter, when the elapsed amount of time has expired, theassigned timer generates an interrupt, sets a flag, or performs otherknown types of indications or alerts to advise the requesting devicethat the specified amount of time has elapsed. One reason that specialhardware resources circuitry 400 includes eight timers is to satisfy thepotential number of timing requests that could occur at any given timein a system that is operating according to Bluetooth specifications.

A second portion of circuitry shown generally at 408 of the specialhardware resources circuitry 400 includes a plurality of clocks andclock operational logic. More specifically, the four clocks include anative Bluetooth clock 416, a native real-time clock 420, an externallydriven Bluetooth clock 424, an externally driven real-time clock 428 anda clock port 430. Additionally, the circuitry shown generally at 408includes a clock operational logic block 432 that controls the operationof the clocks and prompts each of the four clocks 416 through 428 togenerate clock signals and interrupts as required to external devices.

According to one aspect of the present invention, a microsequencer forprocessing Bluetooth communications is formed to have an internal clockfrequency that is equal to 12 MHz. Stated differently, one real-timeclock pulse is 1/12th microseconds long. According to the Bluetoothspecifications, one Bluetooth clock cycle is equal to 312.5microseconds. Exactly two Bluetooth clock cycles, therefore, are equalto 625 microseconds. Here, therefore, 3750 real-time clock pulses areequal to the period of one Bluetooth cycle.

Accordingly, as may be seen, the native real-time clock 420 producesreal-time clock signals to the native Bluetooth clock 416. Similarly,the externally driven real-time clock 428 produces clock signals toexternally driven Bluetooth clock 424. Each of the four clocks isoperable to produce clock signals or interrupts to external devices asdirected by clock operational logic block 432. Each of the clocks iscoupled to produce a clock output from clock port 430.

In order to satisfy Bluetooth requirements, the possibility exists thatmore than one real-time or Bluetooth clock is required. Because theinventor herein has realized that it is advantageous to create separateand independent clocks to maintain flexibility, among other benefits, asecond set of clocks, namely the externally driven real-time clock 428and the externally driven Bluetooth clock 424 are included. Each ofthese two clocks, however, is driven by a received clock signal from anexternal clock source 436 (for example, from an external master whilethe device in which circuitry 400 is installed is operating as a slave.As is known by those skilled in the art, when a device acts a slave, thetiming of operations are determined by an external master. Accordingly,the present invention facilitates receiving clock signals from anexternal master for synchronizing the externally driven real time clock428 to clock signals received from the external master. The synchronizedand externally driven real time clock 428 then drives a Bluetooth clock424 to cause it to be synchronized with the external master's Bluetoothclock.

The clock operational logic module 432 serves to monitor when aninterrupt or time value or flag should be generated by each of the twoBluetooth clocks 416 and 424, as well as each of the two real-timeclocks 420 and 428. As may be seen, the special hardware resourcescircuitry 400, by including four clocks and eight timers in circuitportions 404 and 408 is able to provide significant timing and controlcapability to satisfy Bluetooth operational requirements.

A third portion of special hardware resources circuitry 400 is thecircuitry shown generally at 412. As may be seen, the circuitry showngenerally at 412 includes four registers for storing computational dataand a data storage logic module. More specifically, a multiplexer 442 iscoupled to each of the four registers 444, 448, 452 and 456 todistribute computational data for temporary storage according to controlcommands received from a data storage logic module 440. Thus, themultiplexer 442 is coupled to produce computational data to a 64-bitstorage register 444, a 16-bit storage register 448, a 32-bit storageregister 456 and a 48-bit storage register 452. The multiplexer 442 alsocommunicates with at least one external device that has computationaldata that is to be stored on a temporary basis.

Data storage logic module 440 monitors the size of data that is to betemporarily stored. In the functional block diagram of FIG. 4, a signal460 is conducted to data storage logic module 440 indicating the size ofthe data that is to be temporarily stored. Accordingly, data storagelogic module 440 generates a control signal 464 that is produced todemultiplexer 442 to direct it to route the data packet to one of thefour storage registers 444 through 456.

Because FIG. 4 is functional in nature, the described operation isfunctional in nature and generally represents the logical operation ofthe inventive system. In one embodiment of the invention, themicrosequencer of FIG. 3 implements the functional aspects describedwith respect to the system of FIG. 4. For example, microcode ROM 304 ofFIG. 3 defines computer instructions that direct control decode module316 to generate control commands to cause a data computational value tobe stored in any one of the special hardware registers of specialhardware resources block 328. In one embodiment of the invention, themicrocode defined logic within microcode ROM 304 prompts the controldecode module 316 to store data in registers according to the size ofthe data that is to be stored as has been described for the functionalblock diagram of FIG. 4.

FIG. 5 is a functional schematic block diagram of a microsequencerconfigured as a real-time Bluetooth baseband controller. Amicrosequencer circuit 500 in which the microsequencer is configured asa real-time Bluetooth baseband controller includes a microsequencer 504that is coupled to a plurality of devices. More specifically, as may beseen, microsequencer 504 is coupled to a plurality of buses 508, 518 and516 that enables it to communicate with registers, memory and othercircuitry. For example, bus 508 is coupled to RX audio circuitry 520, RXdata FIFO 524 and E-Buffer 528. E-Buffer 528 further is coupled to radioTX block 532. RX audio circuitry 520, RX data FIFO 524 are for receivingreceived audio processed by the microsequencer. E-Buffer 528 and radioTX 532 are for transmitting radio signals.

The microsequencer 504 of FIG. 5 includes a 72-bitcorrelator/accumulator 504A, a 72-bit arithmetic logic unit 504B andtemporary registers 504C in the diagram shown herein. Microsequencer 504further includes clock circuitry 504D and timer circuitry 504E forproviding timing control functionality to facilitate satisfaction ofBluetooth requirements. The functionality of the clocks and timers are,in the described embodiment of the invention, similar to that which hasbeen described elsewhere herein. Microsequencer 504 further includesmicrocode block 504F that is for storing microcode (operational computerinstructions), access code block 504G that is for storing sync codes andhop frequency block 504H that is for storing frequency information.

Microsequencer 504 also is coupled to CRC FEC Whiten encryption modules536 and 572 that are for providing CRC error detection, error correctionand “whitening” of a given stream of digital signals. The outputs ofmodules 536 and 572 are coupled to logic gates (exclusive OR in thedescribed embodiment) which combines their outputs with data beingoutput from or input to microsequencer 504.

Parameter RAM block 544 and hardware registers block 548 are coupled tobus 516 to enable microsequencer 504 to transmit and receive data andcommands therefrom. Parameter RAM block 544 is random access memory forproviding temporary storage of data. Hardware registers block 548comprises a plurality of accessible registers that are also used forstoring data and/or computer instructions.

Similarly, TX audio block 552, TX data FIFO 556 and E-Buffer block 560also are coupled to bus 518 to communicate with microsequencer 504.E-Buffer 560 further is coupled to receive radio transmissions fromradio RX block 564. Bus 518 is coupled to produce communication signalsto logic gate 568 that is also coupled to receive bits from CRC FECWhiten encryption block 572.

In operation, a signal stream that is to be transmitted is received fromexternal radio circuitry (not shown) at TX audio block 552 or TX dataFIFO block 556. The signal is conducted along bus 518, through logicgate 568 to microsequencer 504. Microsequencer 504, in turn, processesthe signal and outputs it to logic gate 540 where it is logicallycombined with the outputs of CRC FEC Whitten Encryption module 536. Theoutput of the logic gate 540 is then produced to bus 508 which conductsthe signal to E-Buffer 528 and radio TX block 532 for transmission.

Received transmission signals are processed in a similar manner. Areceived signal is conducted into radio RX block 564 for initialprocessing and then into E-Buffer 560. E-Buffer 560 produces the signalto logic gate 568 by way of bus 518 where it is logically combined withthe output of CRC FEC Whitten Encryption module 572 that decodes thesignal (among other functions). The received signal is then conductedthrough microsequencer 504 which then processes it and produces it toeither RX audio block 520 or RX data FIFO block 524 for further audioprocessing.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and detailed description. It should beunderstood, however, that the drawings and detailed description theretoare not intended to limit the invention to the particular formdisclosed, but on the contrary, the invention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the present invention as defined by the claims. As may beseen, the described embodiments may be modified in many different wayswithout departing from the scope or teachings of the invention.

1. A microsequencer for a real-time Bluetooth baseband controller usedto service a plurality of slave devices, comprises: timer circuitry toaccommodate an upper limit of timer requests, the timer circuitryincludes a plurality of timers to facilitate service to each of theplurality of slave devices; temporary data storage circuitry thatincludes a plurality of registers each having a different register size,wherein the temporary data storage circuitry receives computationaldata, and stores the computational data in a register selected from theplurality of registers based upon a size of the computational data; anda plurality of Bluetooth and native clocks coupled to drive the timercircuitry based upon a Bluetooth timing functionality according to aBluetooth specification, wherein the plurality of Bluetooth and nativeclocks drive the timer circuitry to facilitate a Bluetooth timingfunctionality.
 2. The microsequencer of claim 1 wherein the plurality ofnative and externally driven clocks include an external real-time clock,wherein an external master clock drives the external real-time clock. 3.The microsequencer of claim 1 wherein the plurality of registers includea 64-bit register, a 48-bit register, a 32-bit register and a 16-bitregister.
 4. The microsequencer of claim 1 wherein the temporary datastorage circuitry further comprises: a data storage logic module coupledto the plurality of registers, wherein the data storage logic moduleselects the register of the plurality of registers to use based upon thesize of the computational data that is to be temporarily stored.
 5. Themicrosequencer of claim 1 wherein the timers include at least fourtimers.
 6. The microsequencer of claim 1 wherein the timers include atleast eight timers.
 7. The microsequencer of claim 1 further includingtimer control logic circuitry for controlling the operation of the atleast eight timers.